1. Field of the Invention
The present invention relates to an indwelling catheter. More particularly, the present invention relates to an indwelling catheter to be used for inserting through the urethra of an animal or human to the bladder in order to facilitate urination, sampling of the urine from inside of the bladder, or administration of medicines into the bladder.
2. Description of the Related Art
Urination becomes difficult when inflammation is caused in the urethra of animals, such as a dog or cat, or a human body. One method for treating such dysuria is to temporarily insert a catheter through the urethra from the outside to secure passageway for urination. The catheter is also used for treating lesions in the bladder.
FIG. 7a shows the use of a catheter for treating lesions in the bladder of a dog, cat, or the like, wherein the catheter 52 is inserted from the tip of the urethra 51. The reference numerals 53 and 54 denote the bladder and inflammation site caused in the urethra 51. The catheter 52 may be pulled out after the treatment without allowing the catheter 52 to remain in the urethra 51. However, inserting the catheter every time for the treatment may impose a great burden on the animal. Otherwise, the catheter 52 cannot be inserted into the urethra 51 when urethritis is worsened, causing lethal complications that require surgical operation of the abdomen. For countermeasures for such diseases, a stitch margin 55 rovided at both sides of the portion protruding out of the catheter 52 is sewed to the skin in order to permit the catheter 52 to permanently stay in the urethra 51 as shown in FIG. 7b. 
In the case of therapy for a human body, on the other hand, a catheter 62 having a balloon at the tip (balloon catheter) is placed in the urethra 61 as shown in FIG. 8. The reference numeral 63 in the drawing denotes the bladder 63. The tip of the catheter 62 has a elastically expandable and contractible balloon 64, and the catheter 62 also has a branched ventilation hole 65 at the other end. The balloon 64 inserted into the bladder 63 is inflated by sending air from the ventilation hole 65, and retained there by closing the ventilation hole 65 so that the catheter 62 is not pulled out of the urethra 61. When the catheter 62 is pulled out of the urethra 61, air is released by opening the ventilation hole 65 to allow the balloon 64 to contract taking advantage of its elasticity.
A potential catheter for measuring electrocardiograph has been proposed in FIG. 7 of U.S. Pat. No. 5,255,679, wherein a basket having vertical slits is provided in the vicinity at the tip of the tube, the tip of the core wire passing through the inside of the tube is bonded to the tip of the tube, and the basket disposing a number of electrodes is expanded by pulling in and out the core wire.
However, it is difficult to retain the catheter 52 for a long period of time when the stitch margin 55 of the catheter 52 is sewed to the skin of the animal for treating the animal, giving great stress to the animal. When the animal is a male, the penis should be exposed from the foreskin to dry the mucous membrane or to induce other inflammations which require incision of the abdomen or lead the animal to death. While the balloon catheter 62 is not required to be sewed to the skin, on the other hand, the balloon 64 may fail to contract by opening the ventilation hole 65 when, for example, urine components are accumulated on the surface of the balloon 64 to compromise elasticity of the balloon. An operation for forcibly breaking the balloon 64 from under the abdominal cavity is required when the balloon does not contract.
Accordingly, it is an object of the present invention for solving the foregoing problems to provide an indwelling catheter that is not required to be sewed to the skin and is able to retain it in the urethra by a single operation, besides it is easily pulled out of the urethra.
An indwelling catheter according to the present invention comprises a flexible malecot tube having a plurality of slits elongating in the longitudinal direction in the vicinity of the tip of the catheter, a flexible core wire disposed to be freely movable in the axial direction along the malecot tube with its tip fixed to the tip of the malecot tube, a cylindrical connector fixed to the root side of the malecot tube into which the root area of the core wire is inserted, and a stopper provided on the connector in order to constrain arbitrary movement of the core wire.
While the indwelling catheter as described above may have an another passageway different from the flow passageway for permitting a liquid in the malecot tube to flow through, and the core wire may be housed in the former passageway, the core wire is preferably housed in the flow passageway within the malecot tube with remaining a marginal space for allowing the liquid to flow through the flow passageway. The stopper is preferably a rubber member having a hole for allowing the core wire to penetrate so that the rubber member is capable of constraining motion of the core wire by frictional force, and exerting a seal function between the core wire and the connector. Alternatively, the stopper may comprise a member provided on the connector and mechanically engaging with the core wire. An opening for communicating between the inside and outside of the connector and a sealing lid for freely opening and shutting the opening are preferably provided on the side wall of the connector.
The tip of the malecot tube preferably has a member for confirming insertion margin such as an imaging member or a scale or a graduation. More preferably, a knob is attached at the root of the core wire protruding out of the end face of the connector, and the core wire has a snap-off portion for snapping the core wire with some remaining sites protruding out of the end face of the connector when the core wire is pulled out of the root side of connector. The indwelling catheter according to the present invention preferably has a cover for covering the end portion of the remaining snapped core wire on the end face of the connector. More preferably, the root area of the core wire is previously separated into the tip side and root side and these end portions of the separated core wire are connected with a snap-off tube into which both end portions are inserted. A snap point that can be readily snapped is formed at a site a distance shifted from the junction of two core wires in the snap-off tube.
In the indwelling catheter according to the present invention, when the root of the core wire protruding out of the end portion of the connector is pulled with one hand while holding the connector with the other hand, a compression force is applied to the malecot tube, because the tip of the core wire is fixed to the malecot tube. Consequently, tape-shaped sites divided by the slit on the malecot tube are buckled and outwardly expanded by being bent at the center of the tape. The bent configuration is maintained by the action of the stopper. When the root of the core wire is pushed in the tip side, a tensile force is applied to the malecot tube to expand the tape-shaped site and the malecot portion is contracted.
Accordingly, a simple operation is sufficient for retaining the catheter in the urethra, wherein the malecot tube is at first inserted into the urethra until the tip of the malecot tube is enveloped in the bladder, then the malecot part is expanded by pulling the core wire followed by allowing the stopper to operate. This procedure permit the expanded malecot part to be maintained, and the inner wall of the bladder catches the expanded malecot part to securely retain the catheter in the urethra. Labor of a treatable operator is reduced and stress on an animal such as a dog or cat may be alleviated by the process as described above. The main body of the catheter can be gently retained in the body, thereby enabling the therapy period to be reduced and therapeutic ratio to be improved.
Since only the connector portion of the catheter is exposed out of the urethra, the animal neither bites nor licks the connector of the catheter to pull out the catheter. For pulling out the catheter, the expanded malecot portion can be forcibly contracted by pushing the core wire, thereby the catheter can be readily pulled out of the urethra by pulling the contracted catheter.
In the indwelling catheter in which the core tube is housed with a marginal space for allowing the liquid to flow through the malecot tube, the catheter is not particularly required to have a large inner diameter since the flow passage serves as a space for allowing a liquid to flow through and a passageway for inserting the core wire. Instead, the catheter has an approximately the same diameter as conventional catheters. Further, since the catheter has only one inner space, the catheter has a simple construction to be easily manufactured.
In the indwelling catheter in which the catheter in which the stopper is a rubber member having a hole for allowing the core wire to penetrate therethrough in order to seal between the core wire and the connector, motion of the core wire in the axial direction can be constrained by elasticity and frictional resistance of the rubber member. Consequently, intended movement of the core wire can be made easy while reducing the possibility of unintended or arbitrary movement of the core wire. Accordingly, the malecot tube can be easily expanded and contracted with few possibilities of falling down of the indwelling catheter from the urethra as a result of arbitrary expansion of the malecot tube. The stopper has a simple construction and is easily manufactured, since the stopper is merely composed of the rubber member. Another seal member need not be separately provided because the rubber member exerts a seal function between the connector and the core wire. The seal function by the rubber member also prevents invasion of microorganisms from the outside while the catheter is retained. Retention of the indwelling catheter is further secured when the stopper comprises a member mechanically engaging the core wire provided in the connector.
In the indwelling catheter having an opening for communicating between the outside and inside of the side wall of the connector and a sealing lid for freely opening and shutting the opening, sampling of urine and injection of therapeutic agents may be facilitated via the opening. In addition, invasion of microorganisms can be also prevented since the opening can be sealed with the lid while retaining the catheter.
In the indwelling catheter having a member for confirming insertion margin at the tip of the malecot tube, the malecot can be expanded after completely confirming that the malecot portion has been enveloped in the bladder. In the indwelling catheter having a knob attached at the root of the core wire protruding out of the end portion of the connector, wherein the core wire has a snap-off portion for snapping the core wire with some remaining sites protruding out of the end face of the connector when the core wire is pulled out of the root side of connector, the core wire can be easily pulled out of the connector by pulling the knob. Excess protruding portions of the knob and core wire may be easily removed since the core wire can be readily snapped at the snap portion after pulling out the core wire, thereby the animals may hardly bite or lick the knob. The malecot portion of the indwelling catheter that has been once pulled out cannot be expanded again by snapping the core wire at the snap site, thereby possibilities of secondary infection can be eliminated to ensure perfect disposable use of the catheter. In the indwelling catheter having a cover for covering the end portion of the remaining snapped core wire on the end face of the connector, the root of the core wire is protected from being licked by the animal since the root of the core wire is covered with the cover, or the root never damages the skin of the animal.
In the indwelling catheter in which the root area of the core wire is previously separated into the tip side and the root side and these end portions are connected with a snap-off tube into which both end portions are inserted, and in which a snap point readily snapped is formed at a site a distance shifted from the junction of two core wires in the snap-off tube, the snap-off tube is broken at the snap point when a force is applied to the root of the core wire in a bending direction, thereby the core wire can be easily separated into the tip side and root side. In addition, since the site where the core wire is separated is shifted from the snap point of the snap-off tube, the core tube protruding out of the broken part of the snap-off tube can be inserted into the cavity of the other snap-off tube. Accordingly, the root side of the core wire attached with the knob once separated may be temporarily connected to the end portion at the tip side to push the core wire toward the tip side using the knob. The malecot portion can be readily contracted by the operation described above.